The present invention relates to an apparatus useful for texturizing proteins. Meat analog products are well known in the art as are various methods of preparing such meat analog products. Generally, the meat analog products have found some use as substitutes for natural meat products as they often contain less calories and a higher protein content. However, public acceptance and use of the products has still been limited due to the visual appearance of such products. Although developments in the art have enabled one to manufacture meat analog products having superior properties as far as nutrition and cost is concerned, the products still do not possess the desired meat-like or fibrous appearance and texture.
Several different techniques are, as aforementioned, known for making meat analog products. Thus, there is the well known fiber spinning or thermoplastic extrusion technique which is illustrated in U.S. Pat. Nos. 2,682,466; 2,730,447 and 2,730,448. According to this technique, a spinning dope is formed from alkali-treated protein such as soy protein, and the dope is extruded through a dye or membrane into an aqueous precipitating bath which contains an acid and a salt. The acid bath sets the filaments or fibers following which the filaments may be bundled together and stretched to orient the molecular structure of the fibers. Further patents relating to this technique are U.S. Pat. Nos. 3,498,793 and 3,559,561.
A further well known technique for forming meat analog products is illustrated in, among others, U.S. Pat. Nos. 3,488,031; 3,488,770; 3,480,442 and 3,496,858. This technique is basically an adaptation of technology involved in making ready-to-eat cereal food products; a mixture of protein, water anf flavour is prepared whereafter the mixture is fed into a cooker-extruder where it is subjected to heat and pressure and subsequently extruded. Following the extrusion into the atmosphere, the product expands to form a product which has fiber-like material therein.
Recently, there have been further techniques developed for the formation of meat analog products. One such technique is described in U.S. Pat. Nos. 3,814,823 and 3,693,533. These patents describe a process and apparatus for forming a meat-like product wherein a protein mix containing a heat-coagulable protein is formed, the moisture content of the protein mix being adjusted, following which the wet mix is worked to provide a coherent workable protein-containing dough.
The dough is then subjected to a non-turbulent stretching and heat to provide unidirectional parallel meat-like fibers. An apparatus adapted to carry out the method is illustrated in U.S. Pat. No. 3,693,533, which apparatus is a pair of endless belts forming a convergent space therebetween in a first plane and a divergent space in a second plane such that the protein dough fed thereto is decreased in a first dimension and increased in a second dimension to form a slab of meat analog product.
U.S. Pat. No. 3,886,298 teaches a technique of forming meat analog products wherein a wet protein dough is fed to an extruder wherein it is compressed and heated. The dough, when extruded, is subjected to a pressure drop causing expansion of the dough.
A similar process is taught in U.S. Pat. No. 3,886,299 except that the pressure drop upon extrusion is low to minimize the puffing of the product.
It is an object of the present invention to provide an apparatus for texturizing protein, which apparatus produces a meat analog product having the texture and appearance of meat, and wherein the fibers in the product are aligned in a curvi-linear manner.